Eyeglasses are stored in containers and eyeglass cases that are made of materials that are not transparent. Therefore, a person observing the case cannot see the glasses inside the case, if they are in fact in the case. Likewise, the observer cannot observe if the glasses are missing from the case.
With respect to some designs of eyeglass cases, the lack of transparency may not be a problem, because the shape and design of the case is such that, at the least, it suggests that the case holds a pair of eyeglasses. However, even if the design and shape suggests that the case is intended to hold eyeglasses, the lack of transparency does not allow a person to observe whether the glasses are present or not.
However, there is an aesthetic aspect to design that triumphs any or all of originality, innovation, ingenuity and creativity. Products that manifest that aesthetic may not bear any resemblance to the shape previously associated with that object. In view of this, it is possible that newly designed eyeglass cases may not, upon observation, suggest what they might contain. Accordingly, the observer of the container may not realize that the container is intended to contain eyeglasses, or that it in fact contained eyeglasses.